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Non Traditional Machining Processes MIME - 6980

Non Traditional Machining Processes MIME - 6980 . Presented by, Abhijit Thanedar Naga Jyothi Sanku Pritam Deshpande Vijayalayan Krishnan Vishwajeet Randhir. Electron Beam Machining. Introduction - A Brief History.

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Non Traditional Machining Processes MIME - 6980

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  1. Non Traditional Machining ProcessesMIME - 6980 Presented by, • Abhijit Thanedar • Naga Jyothi Sanku • Pritam Deshpande • Vijayalayan Krishnan • Vishwajeet Randhir Electron Beam Machining

  2. Introduction - A Brief History • Development of EB technology is closely related with advances in vacuum engineering and electron optics • In 1905, Marcello von Pirani successfully melted Tantalum • In 1938, magnetic lens were introduced to focus EB • It was only in 1965, all techniques were put together and secured a place in production processes list.

  3. Classification of NTM processes Classification based on the energy source • Mechanical • Electro-chemical • Chemical • Thermo-electric EBM uses Thermo-electric Energy.

  4. GENERATION OF ELECTRON BEAM: The electron beam is formed inside an electron gun, which is basically a triode and consists of: • A cathode which is a hot tungsten filament emitting high negative potential electron • A grid cup, negatively biased with respect to filament , and • An anode at ground potential though which the accelerated electrons pass

  5. Energy Conversion at the point of action electrons are accelerated in the electrostatic field of the beam source to attain a kinetic energy, E = e UB • the kinetic energy absorbed by the electrons during their trajectory through the accelerating field is E = (me0/2) ve2 (1 + 3 ve2/4c2 + 5 ve4/8 c4 +…)= e UB

  6. Relation between velocity and acceleration voltage

  7. BEAM ACTION ON IMPINGEMENT ON MATTER

  8. Machine Tools The three major subsystems that make up an electron beam machining system are • power supply, • electron beam gun, and • the vacuum system.

  9. Modern EBM Drilling Machine

  10. POWER SUPPLY • Pulsed DC • Voltage range up to 150 kv to accelerate electrons • Systems capability can go as high as 12 kw • high-voltage sections of the power supply are submerged in insulating dielectric oil

  11. ELECTRON GUN • gun is designed to be used exclusively for material removal applications and can be operated only in the pulse mode • It has a cathode, bias electrode, anode, magnetic coil/lens (to converge the beam), variable aperture, 3 final magnetic coils (used as magnetic lens, deflection coil, and stigmator) and rotating disc.

  12. Gun Types • 2 electrode gun

  13. 3 Electrode Guns

  14. Rogowski gun Telefocus gun Modified 3 Electrode Guns

  15. Four Electrode Array gun

  16. High-perveance guns Pierce gun

  17. Guns with Curved Electron Trajectories

  18. Guns with Concave Emmiting Surface and center bore in cathode

  19. Beam Guidance

  20. MATHEMATICAL MODEL: Energy of Electrons: The kinetic energy of the electrons can be written as: K.E.=Ee=1/2 mV2. Where, m= mass of electron. e= charge on electron.(joules) E= voltage. V= velocity of electron.(cm/sec)

  21. Number of electrons per second (N): N= I n. Where , I= beam current. n= electron per second per amp current.

  22. Total Power : P= E I Energy Required to vaporize Workpiece: Material removal rate : G = nP/W.(cm3/sec) Where: P = Power.(watts) n= cutting efficiency. W= Specific energy required to vaporize metal. (joules/cm3) W=[C(Tm-20)+C(Tb-Tm)+Hf+Vv] Where: C= Specific Heat, Tm = Melting temperature Tb = Boiling temperature, Hf = Heat of fusion, Hv = Heat of vaporization

  23. MRR Vs POWER

  24. Parameter Zones

  25. Parameters and their influence Power density

  26. Drilling of all materials

  27. Parameters for drilling various materials

  28. Examples of EBM Drilling

  29. Examples of EBM Drilling

  30. Examples of EBM Drilling

  31. Examples of EBM Drilling

  32. Hole Diameter Vs Pulse Charge

  33. Depth & Diameter Vs Beam Current

  34. Depth of Cut, Milling Width Vs Input Energy

  35. Relation between material thickness s, hole diameter dB, and perforation rate ns

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